Manchester Untied manager Louis van Gaal was left frustrated after his team failed to convert chances and possession into goals as they lost 2-1 to Swansea City on Saturday.

The Red Devils started the game well and took the lead through Ander Herrera, but were put on the back foot when Ki Sung-Yeung grabbed an equaliser with a clinical close-range finish.

The Old Trafford club enjoyed majority of the possession in the second half and created most of the chances, but it was the Swans that drew first-blood in the second period with Bafetimbi Gomes deflecting a Jonjo Shelvey long-range strike past David de Gea.

United had 18 shots on goal during the entire game, but only three out of those were on target. They also had 10 corners and enjoyed 64% of the possession. Van Gaal hailed the second-half performance of his team as the best of the season, but the lack of decisiveness in front of goal was pin-pointed by the manager as the sole reason for the loss.

"I think it was our best second-half [performance], we created a lot of chances and dominated the game but we didn't score," Van Gaal told United's official site.

"That's football, you have to score out of the chances you create. We had a lot of chances, especially in the second half, but they scored and then you know that it shall be difficult."

"I shall say to the players that it is very disappointing but, in the process of the development of our play, then it was a very good match," the Dutchman added.

"To play like this, so dominant, creating so many chances, you can hardly improve apart from scoring goals, but that is also a bit of luck."

The loss against the South Wales side and victory for Arsenal over Crystal Palace sees the north London club overtake their rivals into third place. And a victory for Southampton over Liverpool on Sunday will see United knocked out of the top four for the first time since November.